US20170335419A1 - Stainless steel strip for flapper valves - Google Patents
Stainless steel strip for flapper valves Download PDFInfo
- Publication number
- US20170335419A1 US20170335419A1 US15/102,217 US201515102217A US2017335419A1 US 20170335419 A1 US20170335419 A1 US 20170335419A1 US 201515102217 A US201515102217 A US 201515102217A US 2017335419 A1 US2017335419 A1 US 2017335419A1
- Authority
- US
- United States
- Prior art keywords
- strip
- steel
- mpa
- strip according
- following requirements
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0236—Cold rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/02—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for springs
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F1/00—Springs
- F16F1/02—Springs made of steel or other material having low internal friction; Wound, torsion, leaf, cup, ring or the like springs, the material of the spring not being relevant
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F1/00—Springs
- F16F1/02—Springs made of steel or other material having low internal friction; Wound, torsion, leaf, cup, ring or the like springs, the material of the spring not being relevant
- F16F1/021—Springs made of steel or other material having low internal friction; Wound, torsion, leaf, cup, ring or the like springs, the material of the spring not being relevant characterised by their composition, e.g. comprising materials providing for particular spring properties
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
- C21D1/607—Molten salts
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/004—Dispersions; Precipitations
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
Definitions
- the invention relates to a stainless steel strip for flapper valves in compressors and other reed applications.
- Flapper or reed valves are used in various types of applications where a specific type of compression cycle is regulated for a specific purpose. It can be a refrigeration cycle in a hermetic reciprocating compressor working uninterrupted in a refrigerator or in the air conditioner of a car.
- a flapper valve is basically a spring made from a pre-hardened steel strip. In its simplest form, the flapper valve is tongue shaped, where one end is fixed and the opposite end hangs free and regulates the liquid or gas flow in the compressor.
- the flapper valve suffers from both cyclic bending stresses and cyclic impact stresses during its service. Usually, these cyclic stresses eventually cause fatigue failure. Accordingly, the fatigue properties are of the utmost importance for the flapper valve material.
- a flapper valve made of a steel strip of this invention has its fatigue properties optimized by a combined effect of modifications to the chemical composition of the steel, the non-metallic inclusions and the heat treatment.
- Compressor OEMs require materials that have a higher fatigue life to improve the compressor's performance and life.
- COP coefficient of performance
- the existing steel grades used for reed valves are modified versions of a carbon steel AISI 1095 and a stainless steel AISI 420 produced via conventional melting, casting, rolling and heat treatment processes.
- the industry demands and resulting performance requirements mean that future flapper reeds will increasingly need to be made out of very thin steel strip with an increased fatigue life expectancy and higher damping properties.
- the general object of the present invention is to provide a pre-hardened stainless steel strip for flapper valves having an optimized property profile such that it can be used to produce more efficient and reliable compressors.
- a further object is to provide pre-hardened stainless steel strip for flapper valves, which reduces the flapper reed contribution to the overall noise levels of the compressor.
- Carbon is to be present in a minimum content of 0.3%, preferably at least 0.32, 0.34, 0.36 or 0.36%.
- Carbon is a strong austenite stabilizer with relatively large solubility in austenite.
- the upper limit for carbon is 0.5% and may be set to 0.48, 0.46, 0.44 or 0.42%.
- a referred range is 0.35-0.41%.
- the amount of carbon should be controlled such that the amount of primary carbides of the type M 23 C 6 , M 7 C 3 and M 6 C in the steel is limited, preferably the steel is free from such primary carbides.
- Si is used for deoxidation.
- Si is a strong ferrite former and increases the carbon activity.
- Si is also a powerful solid-solution strengthening element and strengthens the steel matrix. This effect appears at a content of 0.2% Si.
- a preferred range is 0.30-0.60%.
- Manganese is an austenite stabilizer and contributes to improving the hardenability of the steel. Manganese shall therefore be present in a minimum content of 0.2%, preferably at least 0.3, 0.35 or 0.4%. When the content of Mn is too large the amount of retained austenite after finish annealing may be too high.
- the steel shall therefore contain maximum 1.0% Mn, preferably maximum 0.8, 0.7 or 0.65%.
- Chromium is a ferrite stabilizing element, which is added to impart corrosion resistance to the steel. Cr needs to be present in a content of at least 12.0% in order to provide a passive film on the steel surface. The lower limit may be 12, 4, 12, 6, 12, 8 or 13%. When the content of Cr exceeds 15%, however, delta ferrite may form.
- Mo is a ferrite stabilizer and is known to have a very favourable effect on the hardenability. Molybdenum is essential for attaining a good secondary hardening response. The minimum content is 0.5% and may be set to 0.6, 0.7 or 0.8%. Molybdenum is strong carbide forming element and also a strong ferrite former. The maximum content of molybdenum is therefore 2.0%. Preferably Mo is limited to 1.5, 1.83 or 1.1%.
- Vanadium forms evenly distributed fine precipitated carbides, nitrides and carbonitrides of the type V(N,C) in the matrix of the steel.
- This hard phase may also be denoted MX, wherein M is mainly V but other metals like Cr and Mo may be present to some extent.
- X is one or both of C and N. Vanadium shall therefore be present in an amount of 0.01-0.2%.
- the upper limit may be set to 0.1 or 0.08%.
- the lower limit may be 0.02, 0.03, 0.04 or 0.05%.
- Nitrogen is a strong austenite former. N is restricted to 0.15% in order to obtain the desired type and amount of hard phases, in particular V(C,N). Higher nitrogen content may lead to work hardening, edge cracking and/or a high amount of retained austenite.
- vanadium rich carbonitrides V(C,N) will form. These will be partly dissolved during the austenitizing step and then precipitated during the tempering step as particles of nanometre size.
- the thermal stability of vanadium carbonitrides is considered to be better than that of vanadium carbides. Therefore the resistance against grain growth at high austenitizing temperatures is enhanced.
- the lower limit may be 0.02, 0.03, 0.04 or 0.05%.
- the upper limit may be 0.12, 0.10, 0.08 or 0.06%.
- Nickel is an austenite former. Ni may be present in an amount of ⁇ 2.0%. It gives the steel a good hardenability and toughness. However, because of the expense, the nickel content of the steel should be limited. The upper limit may therefore be set to 1.0, 0.5 or 0.5%. However, Ni is normally not deliberately added.
- Cobalt is an austenite former. Co causes the solidus temperature to increase and therefore provides an opportunity to raises the hardening temperature. During austenitization it is therefore possible to dissolve larger fraction of carbides and thereby enhance the hardenability. Co also increases the Ms temperature. However, large amount of Co may result in a decreased toughness and wear resistance. The maximum amount is 2% and may be set to 0.5%. However, for practical reasons, such as scrap handling, a deliberate addition of Co is normally not made.
- Cu is an austenite stabilizing element but has a low solubility in ferrite. Cu may contribute to increasing the hardness and the corrosion resistance of the steel. However, it is not possible to extract copper from the steel once it has been added. This drastically makes the scrap handling more difficult. For this reason, the upper limit may be 1.0, 0.5, or 0.3%. Copper is normally not deliberately added.
- Aluminium may be used for deoxidation in combination with Si and Mn.
- the lower limit is set to 0.001, 0.003, 0.005 or 0.007% in order to ensure a good deoxidation.
- the upper limit is restricted to 0.06% for avoiding precipitation of undesired phases such as AlN and hard, brittle Alumina inclusions.
- the upper limit may be 0.05, 0.04, 0.03, 0.02 or 0.015%.
- molybdenum may be replaced by twice as much with tungsten because of their chemical similarities.
- tungsten is expensive and it also complicates the handling of scrap metal.
- the maximum amount is therefore limited to 2%, preferably 0.5% or 0.3% and most preferably no deliberate additions are made.
- Niobium is similar to vanadium in that it forms carbonitrides of the type M(N,C) and may in principle be used to replace part of the vanadium but that requires the double amount of niobium as compared to vanadium.
- Nb results in a more angular shape of the M(N,C) and these are also much more stable than V(C,N) and may therefore not be dissolved during austenitising.
- the maximum amount is therefore 0.05%, preferably 0.01% and most preferably no deliberate additions are made.
- These elements are carbide formers and may be present in the alloy in the claimed ranges for altering the composition of the hard phases. However, normally none of these elements are added.
- P, S and O are the main impurities, which have a negative effect on the mechanical properties of the steel strip.
- P may therefore be limited to 0.03%, preferably to 0.01%.
- S may be limited to 0.03, 0.01, 0.008, 0.0005 or 0.0002%.
- O may be limited to 0.003, 0.002 or 0.001%.
- the present inventors have systematically investigated the effect of a modified chemical composition and a modified heat treatment on the mechanical properties of the flapper valve material.
- the modifications made to the chemical composition relative to the conventional material were mainly focused on increases in nitrogen and vanadium although some benefits were also gained from increases in austenite levels and tighter control over such elements as carbon, manganese and phosphorus.
- the inventive steel strip can be used for producing flapper valves for compressors having improved properties.
Abstract
The invention relates to a cold roiled and hardened martensitic/austenitic stainless steel strip for flapper valves in the compressors, wherein the steel strip is made from steel combining, in weight % (wt. %), the following elements: C 0.3-0.5, Si 0.2-0.8, Mn 0.2-1.0, Cr 12.0-15.0, Mo 0.50-2.00, N 0.02-0.15, and V 0.01-0.20. The steel has a matrix consisting of tempered martensite and between 5 and 15 volume % austenite and a tensile strength (Rm) of 1970-2300 MPa.
Description
- The invention relates to a stainless steel strip for flapper valves in compressors and other reed applications.
- Flapper or reed valves are used in various types of applications where a specific type of compression cycle is regulated for a specific purpose. It can be a refrigeration cycle in a hermetic reciprocating compressor working uninterrupted in a refrigerator or in the air conditioner of a car. A flapper valve is basically a spring made from a pre-hardened steel strip. In its simplest form, the flapper valve is tongue shaped, where one end is fixed and the opposite end hangs free and regulates the liquid or gas flow in the compressor. The flapper valve suffers from both cyclic bending stresses and cyclic impact stresses during its service. Usually, these cyclic stresses eventually cause fatigue failure. Accordingly, the fatigue properties are of the utmost importance for the flapper valve material.
- A flapper valve made of a steel strip of this invention has its fatigue properties optimized by a combined effect of modifications to the chemical composition of the steel, the non-metallic inclusions and the heat treatment.
- Compressor OEMs require materials that have a higher fatigue life to improve the compressor's performance and life.
- Furthermore, there is a growing interest in the industry to develop more energy efficient and quieter compressors. The coefficient of performance (COP) can be increased by increasing the valve lift and by reducing the thickness of the valves. Compressor designers therefore require valve materials that have enhanced damping properties in addition to fatigue strength improvement.
- The existing steel grades used for reed valves are modified versions of a carbon steel AISI 1095 and a stainless steel AISI 420 produced via conventional melting, casting, rolling and heat treatment processes. However, the industry demands and resulting performance requirements mean that future flapper reeds will increasingly need to be made out of very thin steel strip with an increased fatigue life expectancy and higher damping properties.
- The general object of the present invention is to provide a pre-hardened stainless steel strip for flapper valves having an optimized property profile such that it can be used to produce more efficient and reliable compressors.
- A further object is to provide pre-hardened stainless steel strip for flapper valves, which reduces the flapper reed contribution to the overall noise levels of the compressor.
- It is also an object of the present invention to provide a method of producing such an improved steel strip.
- The foregoing objects, as well as additional advantages are achieved to a significant measure by providing a cold rolled and hardened martensitic stainless steel strip having a composition, microstructure and physical properties as set out in the claims.
- The invention is defined in the claims.
- The importance of the separate elements and their interaction with each other as well as the limitations of the chemical ingredients of the claimed alloy are briefly explained in the following. All percentages for the chemical composition of the steel are given in weight % (wt. %) throughout the description. The amount of microstructural phases is given in volume % (vol. %). Upper and lower limits of the individual elements can be freely combined within the limits set out in the claims.
- is to be present in a minimum content of 0.3%, preferably at least 0.32, 0.34, 0.36 or 0.36%. Carbon is a strong austenite stabilizer with relatively large solubility in austenite. The upper limit for carbon is 0.5% and may be set to 0.48, 0.46, 0.44 or 0.42%. A referred range is 0.35-0.41%. In any case, the amount of carbon should be controlled such that the amount of primary carbides of the type M23C6, M7C3 and M6C in the steel is limited, preferably the steel is free from such primary carbides.
- Silicon is used for deoxidation. Si is a strong ferrite former and increases the carbon activity. Si is also a powerful solid-solution strengthening element and strengthens the steel matrix. This effect appears at a content of 0.2% Si. A preferred range is 0.30-0.60%.
- Manganese is an austenite stabilizer and contributes to improving the hardenability of the steel. Manganese shall therefore be present in a minimum content of 0.2%, preferably at least 0.3, 0.35 or 0.4%. When the content of Mn is too large the amount of retained austenite after finish annealing may be too high. The steel shall therefore contain maximum 1.0% Mn, preferably maximum 0.8, 0.7 or 0.65%.
- Chromium is a ferrite stabilizing element, which is added to impart corrosion resistance to the steel. Cr needs to be present in a content of at least 12.0% in order to provide a passive film on the steel surface. The lower limit may be 12, 4, 12, 6, 12, 8 or 13%. When the content of Cr exceeds 15%, however, delta ferrite may form.
- Mo is a ferrite stabilizer and is known to have a very favourable effect on the hardenability. Molybdenum is essential for attaining a good secondary hardening response. The minimum content is 0.5% and may be set to 0.6, 0.7 or 0.8%. Molybdenum is strong carbide forming element and also a strong ferrite former. The maximum content of molybdenum is therefore 2.0%. Preferably Mo is limited to 1.5, 1.83 or 1.1%.
- Vanadium forms evenly distributed fine precipitated carbides, nitrides and carbonitrides of the type V(N,C) in the matrix of the steel. This hard phase may also be denoted MX, wherein M is mainly V but other metals like Cr and Mo may be present to some extent. X is one or both of C and N. Vanadium shall therefore be present in an amount of 0.01-0.2%. The upper limit may be set to 0.1 or 0.08%. The lower limit may be 0.02, 0.03, 0.04 or 0.05%.
- Nitrogen is a strong austenite former. N is restricted to 0.15% in order to obtain the desired type and amount of hard phases, in particular V(C,N). Higher nitrogen content may lead to work hardening, edge cracking and/or a high amount of retained austenite. When the nitrogen content is properly balanced against the vanadium content, vanadium rich carbonitrides V(C,N) will form. These will be partly dissolved during the austenitizing step and then precipitated during the tempering step as particles of nanometre size. The thermal stability of vanadium carbonitrides is considered to be better than that of vanadium carbides. Therefore the resistance against grain growth at high austenitizing temperatures is enhanced. The lower limit may be 0.02, 0.03, 0.04 or 0.05%. The upper limit may be 0.12, 0.10, 0.08 or 0.06%.
- Nickel is an austenite former. Ni may be present in an amount of ≦2.0%. It gives the steel a good hardenability and toughness. However, because of the expense, the nickel content of the steel should be limited. The upper limit may therefore be set to 1.0, 0.5 or 0.5%. However, Ni is normally not deliberately added.
- Cobalt is an austenite former. Co causes the solidus temperature to increase and therefore provides an opportunity to raises the hardening temperature. During austenitization it is therefore possible to dissolve larger fraction of carbides and thereby enhance the hardenability. Co also increases the Ms temperature. However, large amount of Co may result in a decreased toughness and wear resistance. The maximum amount is 2% and may be set to 0.5%. However, for practical reasons, such as scrap handling, a deliberate addition of Co is normally not made.
- Cu is an austenite stabilizing element but has a low solubility in ferrite. Cu may contribute to increasing the hardness and the corrosion resistance of the steel. However, it is not possible to extract copper from the steel once it has been added. This drastically makes the scrap handling more difficult. For this reason, the upper limit may be 1.0, 0.5, or 0.3%. Copper is normally not deliberately added.
- Aluminium may be used for deoxidation in combination with Si and Mn. The lower limit is set to 0.001, 0.003, 0.005 or 0.007% in order to ensure a good deoxidation. The upper limit is restricted to 0.06% for avoiding precipitation of undesired phases such as AlN and hard, brittle Alumina inclusions. The upper limit may be 0.05, 0.04, 0.03, 0.02 or 0.015%.
- In principle, molybdenum may be replaced by twice as much with tungsten because of their chemical similarities. However, tungsten is expensive and it also complicates the handling of scrap metal. The maximum amount is therefore limited to 2%, preferably 0.5% or 0.3% and most preferably no deliberate additions are made.
- Niobium is similar to vanadium in that it forms carbonitrides of the type M(N,C) and may in principle be used to replace part of the vanadium but that requires the double amount of niobium as compared to vanadium. However, Nb results in a more angular shape of the M(N,C) and these are also much more stable than V(C,N) and may therefore not be dissolved during austenitising. The maximum amount is therefore 0.05%, preferably 0.01% and most preferably no deliberate additions are made.
- Ti, Zr and Ta (≦0.05% each)
- These elements are carbide formers and may be present in the alloy in the claimed ranges for altering the composition of the hard phases. However, normally none of these elements are added.
- B may be used in order to further increase the hardness of the steel. The amount is limited to 0.01%, preferably ≦0.005 or even ≦0.001%.
- These elements may be added to the steel in the claimed amounts in order to further improve the hot workability and to modify the shape of non-metallic inclusions.
- P, S and O are the main impurities, which have a negative effect on the mechanical properties of the steel strip. P may therefore be limited to 0.03%, preferably to 0.01%. S may be limited to 0.03, 0.01, 0.008, 0.0005 or 0.0002%. O may be limited to 0.003, 0.002 or 0.001%.
- The present inventors have systematically investigated the effect of a modified chemical composition and a modified heat treatment on the mechanical properties of the flapper valve material. The modifications made to the chemical composition relative to the conventional material were mainly focused on increases in nitrogen and vanadium although some benefits were also gained from increases in austenite levels and tighter control over such elements as carbon, manganese and phosphorus.
- The continuous hardening of valve strip was undertaken using different furnace parameters to map the hardening response of material from the conventional and modified chemical compositions. The production trials were carried out at a constant line speed with hardening temperatures in the range from 1000° C. to 1080° C., quenching into a molten lead alloy at a temperature in the range of 250° C. to 350° C. and tempering at temperatures in the range from 220° C. to 600° C.
- The mechanical properties resulting from these hardening trials on conventional material corresponded to:
-
- a yield strength Rp0.2 range between 1300 MPa and 1600 MPa.
- a tensile strength Rm range between 1740 MPa and 2100 MPa
- an elongation A50 range between 4% and 6%
- Further continuous hardening trials were carried out on material with the modified chemical composition and non-metallic inclusion content. The production trials were carried out at a constant line speed with hardening temperatures in the range from 1050° C. to 1100° C., quenching into a molten lead alloy at a temperature in the range of 250° C. to 350° C. and tempering at temperatures in the range from 220° C. to 600° C.
- The mechanical properties resulting from further hardening trials on material with the modified chemical composition and non-metallic inclusion content corresponded to:
-
- a Rp0.2 range between 1400 MPa and 1750 MPa,
- a Rm range between 1970 MPa and 2300 MPa
- a A50 range between 4% and 8%
- In this example a stainless steel strip according to the invention is compared to a conventional stainless steel strip. The composition of the investigated steels was as follows:
-
Conventional Inventive C 0.38 0.40 Si 0.36 0.42 Mn 0.48 0.56 Cr 13.1 13.4 Mo 0.98 0.99 N 0.017 0.052 V 0.009 0.055 Ni 0.31 0.15 P 0.018 0.018 S 0.0004 0.0006 - Fe and Impurities Balance.
- The cold rolled strips used for the hardening and tempering trials all had a thickness of 0.203 mm and a width of 140 mm. The strips were subjected to hardening and tempering in the above mentioned continuous hardening furnace. Tensile strength measurements were made according to ISO 6892:2009.
FIG. 1 discloses tensile properties as a function of the austenitising temperature.FIG. 2 discloses the tensile properties as a function of the tempering temperature. - The inventive steel strip can be used for producing flapper valves for compressors having improved properties.
Claims (12)
1. A cold rolled and hardened martensitic/austenitic stainless steel strip for flapper valves in the compressors, wherein the steel strip
a) is made from steel consisting of, in weight % (wt. %):
C 0.3-0.5
Si 0.2-0.8
Mn 0.2-1.0
Cr 12.0-15.0
Mo 0.5-2.0
N 0.02-0.15
V 0.01-0.20
Ni≦2.0
Co≦2.0
Cu≦2.0
W≦2.0
Al≦0.06
Ti≦0.05
Zr≦0.05
Nb≦0.05
Ta≦0.05
B≦0.01
Ca≦0.009
REM≦0.2
Fe and impurities balance,
b) has a matrix consisting of tempered martensite and between 5 and 15 volume % austenite,
c) has a tensile strength (Rm) of 1970-2300 MPa, and
d) has a thickness of 0.07-3 mm and a width of ≦500 mm.
2. A strip according to claim 1 , fulfilling at least one of the following requirements:
C 0.35-0.41
Si 0.30-0.60
Mn 0.40-0.65
Cr 13-14
Mo 0.8-1.2
N 0.03-0.13
V 0.02-0.10
Ni≦0.5
Co≦50.5
Cu≦0.5
W≦0.5
Al≦50.01
Ti≦0.01
Zr≦0.01
Nb≦0.01
Ta≦0.01
B≦0.001
Ca 0.0005-0.002
and wherein the impurity contents of P, S and O fulfils the following requirements
P≦0.03
S≦0.03 and
O≦0.003.
3. A strip according to claim 1 , fulfilling the following requirements:
C 0.35-0.41
Si 0.30-0.60
Mn 0.40-0.65
Cr 13-14
Mo 0.8-1.2
N 0.03-0.10 and
V 0.03-0.09.
4. A strip according to claim 1 , fulfilling at least one of the following requirements:
a tensile strength (Rm) of 2000-2200 MPa,
a yield strength (RP0.2) of 1500-1750 MPa,
a Vickers Hardness (HV1) of 570-650, and
a ductility A50 of 4-9%.
5. A strip according to claim 1 , fulfilling the following requirements:
reverse bending fatigue is >850 MPa.
6. A strip according to claim 1 , having a thickness of 0.1-1.5 mm and/or a width of 5-150 mm.
7. A strip according to claim 1 , wherein the maximum globular inclusion size is 6 μm.
8. A strip according to claim 1 , wherein the primary inclusion species are Silicate type with a maximum width of 4 μm.
9. A method of producing a strip according to claim 1 , wherein the method comprises the following steps:
a) Hot rolling a steel having a composition as defined in claim 1 ,
b) Cold rolling the hot rolled strip to a thickness of 0.07-3 mm,
c) Continuously hardening and tempering the cold rolled strip, and
d) Optionally, slitting the cold rolled strip.
10. A method according claim 9 , wherein the austenitising temperature is 1000-1150° C. in step c) and wherein tempering temperature is 200-600° C.
11. A method according claim 9 , wherein the hardening involves quenching the strip in a bath of molten lead or lead alloy, the bath preferably holding a temperature of 250-350° C.
12. A method according to claim 9 , wherein the steel used is produced by powder metallurgy and wherein the maximum globular inclusion size of said steel is 6 μm.
Applications Claiming Priority (7)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP14196949.3 | 2014-12-09 | ||
EP14196949 | 2014-12-09 | ||
EP14196949.3A EP3031942B1 (en) | 2014-12-09 | 2014-12-09 | Stainless steel strip for flapper valves |
SE1551093A SE1551093A1 (en) | 2015-08-25 | 2015-08-25 | Stainless steel strip for flapper valves |
SE1551093-6 | 2015-08-25 | ||
SE1551093 | 2015-08-25 | ||
PCT/SE2015/051316 WO2016093762A1 (en) | 2014-12-09 | 2015-12-08 | Stainless steel for flapper valves |
Publications (2)
Publication Number | Publication Date |
---|---|
US20170335419A1 true US20170335419A1 (en) | 2017-11-23 |
US9890436B2 US9890436B2 (en) | 2018-02-13 |
Family
ID=56107805
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US15/102,217 Active US9890436B2 (en) | 2014-12-09 | 2015-12-08 | Stainless steel strip for flapper valves |
Country Status (7)
Country | Link |
---|---|
US (1) | US9890436B2 (en) |
JP (1) | JP6196381B2 (en) |
KR (1) | KR102274408B1 (en) |
CN (1) | CN105934530B (en) |
BR (1) | BR112016015645B1 (en) |
SG (1) | SG11201703857WA (en) |
WO (1) | WO2016093762A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN115023510A (en) * | 2020-01-27 | 2022-09-06 | 日立金属株式会社 | Method for producing martensitic stainless steel strip and martensitic stainless steel strip |
Families Citing this family (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN106319385A (en) * | 2016-09-30 | 2017-01-11 | 无锡市明盛强力风机有限公司 | Metal material and preparation method thereof |
CN108277432A (en) * | 2018-03-01 | 2018-07-13 | 武汉科技大学 | A kind of cutlery martensite containing nitrogen stainless steel and its manufacturing method |
SE541912C2 (en) * | 2018-05-28 | 2020-01-07 | Damasteel Ab | Blank for a damascus patterned article |
CN116144895A (en) * | 2018-11-14 | 2023-05-23 | 育材堂(苏州)材料科技有限公司 | High strength stainless steel, heat treatment process and formed member |
CN112501491A (en) * | 2019-09-16 | 2021-03-16 | 山特维克材料技术公司 | Martensitic stainless steel alloy |
US20220235444A1 (en) * | 2019-06-05 | 2022-07-28 | Ab Sandvik Materials Technology | A martensitic stainless alloy |
CN112251682B (en) * | 2020-09-29 | 2022-03-18 | 中国科学院金属研究所 | Ultrahigh-strength nanocrystalline 20Cr13W3Co2 stainless steel and preparation method thereof |
CN114480952B (en) * | 2020-11-13 | 2023-04-07 | 中国科学院金属研究所 | High-strength high-toughness Cu-containing low-carbon martensitic stainless steel and heat treatment process thereof |
CN114032451A (en) * | 2021-09-25 | 2022-02-11 | 浙江吉森金属科技有限公司 | Stainless steel for valve plate and preparation method thereof |
CN114196875B (en) * | 2021-09-25 | 2022-10-28 | 浙江吉森金属科技有限公司 | Stainless steel for valve plate and heat treatment method thereof |
Family Cites Families (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1223150A (en) * | 1968-06-19 | 1971-02-24 | Uddeholms Ab | Method of producing resilient steel strip, and strip formed thereby |
JPH01275737A (en) * | 1988-04-27 | 1989-11-06 | Daido Steel Co Ltd | High strength stainless steel having excellent cold workability |
JPH0448050A (en) * | 1990-06-14 | 1992-02-18 | Daido Steel Co Ltd | Spring steel strip |
JP3012949B2 (en) | 1991-07-19 | 2000-02-28 | 金井 宏之 | Loom lead material |
MY114984A (en) * | 1995-01-13 | 2003-03-31 | Hitachi Metals Ltd | High hardness martensitic stainless steel with good pitting corrosion resistance |
KR100210522B1 (en) * | 1995-01-13 | 1999-07-15 | 다나카 히사노리 | High hardness martensitic stainless steel with good pitting corrosion resistance |
JP3219128B2 (en) | 1996-03-19 | 2001-10-15 | 日新製鋼株式会社 | High-strength martensitic stainless steel with excellent antibacterial properties |
JPH1018001A (en) | 1996-07-01 | 1998-01-20 | Hitachi Metals Ltd | High hardness martensitic stainless steel excellent in pitting corrosion resistance |
JPH1018002A (en) * | 1996-07-01 | 1998-01-20 | Hitachi Metals Ltd | High hardness martensitic stainless steel excellent in pitting corrosion resistance |
JP3587330B2 (en) | 1996-10-03 | 2004-11-10 | 日立金属株式会社 | High hardness martensitic stainless steel with excellent pitting resistance |
JPH10275737A (en) | 1997-03-28 | 1998-10-13 | Toshiba Corp | Ceramic element and its manufacture |
JP3452354B2 (en) * | 2000-01-20 | 2003-09-29 | 日本高周波鋼業株式会社 | Martensitic stainless steel for piston rings and deformed wires for piston rings |
EP1739199B1 (en) | 2005-06-30 | 2009-06-24 | OUTOKUMPU, Oyj | Martensitic stainless steel |
FR2896514B1 (en) | 2006-01-26 | 2008-05-30 | Aubert & Duval Soc Par Actions | STAINLESS STEEL MARTENSITIC STEEL AND METHOD FOR MANUFACTURING A WORKPIECE IN THIS STEEL, SUCH AS A VALVE. |
JP2008133499A (en) * | 2006-11-27 | 2008-06-12 | Daido Steel Co Ltd | High-hardness martensitic stainless steel |
JP5235452B2 (en) * | 2008-02-28 | 2013-07-10 | 新日鐵住金ステンレス株式会社 | Martensitic stainless steel for loom parts with excellent corrosion resistance and wear resistance and method for producing the steel strip |
JP5338169B2 (en) * | 2008-07-17 | 2013-11-13 | 大同特殊鋼株式会社 | High nitrogen martensitic stainless steel |
CN102337461B (en) * | 2010-07-23 | 2013-10-16 | 宝山钢铁股份有限公司 | High-hardness martensitic stainless steel and its production method |
CN103614649B (en) * | 2013-12-06 | 2015-09-30 | 东北大学 | A kind of high-strong toughness high-strength plasticity Martensite Stainless Steel and preparation method thereof |
-
2015
- 2015-12-08 JP JP2016535110A patent/JP6196381B2/en not_active Ceased
- 2015-12-08 KR KR1020177018768A patent/KR102274408B1/en active IP Right Grant
- 2015-12-08 CN CN201580003829.XA patent/CN105934530B/en active Active
- 2015-12-08 BR BR112016015645-5A patent/BR112016015645B1/en active IP Right Grant
- 2015-12-08 WO PCT/SE2015/051316 patent/WO2016093762A1/en active Application Filing
- 2015-12-08 SG SG11201703857WA patent/SG11201703857WA/en unknown
- 2015-12-08 US US15/102,217 patent/US9890436B2/en active Active
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN115023510A (en) * | 2020-01-27 | 2022-09-06 | 日立金属株式会社 | Method for producing martensitic stainless steel strip and martensitic stainless steel strip |
EP4098757A4 (en) * | 2020-01-27 | 2023-12-27 | Proterial, Ltd. | Method for producing martensitic stainless steel strip, and martensitic stainless steel strip |
Also Published As
Publication number | Publication date |
---|---|
BR112016015645A2 (en) | 2017-08-08 |
KR102274408B1 (en) | 2021-07-06 |
JP6196381B2 (en) | 2017-09-13 |
BR112016015645A8 (en) | 2020-06-02 |
KR20170092675A (en) | 2017-08-11 |
CN105934530B (en) | 2017-08-08 |
WO2016093762A1 (en) | 2016-06-16 |
BR112016015645B1 (en) | 2022-12-13 |
CN105934530A (en) | 2016-09-07 |
JP2017508863A (en) | 2017-03-30 |
US9890436B2 (en) | 2018-02-13 |
SG11201703857WA (en) | 2017-06-29 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US9890436B2 (en) | Stainless steel strip for flapper valves | |
US10577671B2 (en) | High-hardness hot-rolled steel product, and a method of manufacturing the same | |
KR100912570B1 (en) | High-strength hot-dip galvanized steel sheet excellent in formability and method for producing same | |
JP4650013B2 (en) | Abrasion resistant steel plate with excellent low temperature toughness and method for producing the same | |
CN111479945B (en) | Wear-resistant steel having excellent hardness and impact toughness and method for manufacturing same | |
JP5076683B2 (en) | High toughness high speed tool steel | |
EP3031942B1 (en) | Stainless steel strip for flapper valves | |
WO2017111680A1 (en) | Hot work tool steel | |
SE541151C2 (en) | Stainless steel | |
JP4645307B2 (en) | Wear-resistant steel with excellent low-temperature toughness and method for producing the same | |
CN113166901B (en) | Chromium-molybdenum steel plate with excellent creep strength and preparation method thereof | |
KR102031443B1 (en) | Wear resistant steel having excellent hardness and impact toughness and method of manufacturing the same | |
JP4645306B2 (en) | Wear-resistant steel with excellent low-temperature toughness and method for producing the same | |
WO2021251892A1 (en) | Hot work tool steel | |
CN113966405A (en) | Martensitic stainless steel alloy | |
US10487380B2 (en) | High-strength special steel | |
KR101795277B1 (en) | High strength spring steel having excellent corrosion resistance | |
KR101776491B1 (en) | High strength spring steel having excellent corrosion resistance | |
SE1551093A1 (en) | Stainless steel strip for flapper valves | |
EP3980571A1 (en) | Steel strip for flapper valves | |
RU2813064C1 (en) | Method for producing high-strength steel sheet | |
KR102418039B1 (en) | Ultra high strength steel deformed bar and manufacturing method thereof | |
KR20230125712A (en) | Chromium-molybdenum steel having excellent strength and ductility and manufacturing the same |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: VOESTALPINE PRECISION STRIP AB, SWEDEN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:MILLWARD, CHRIS;NAWAZ, AZHAR;LOF, ALEXANDER;SIGNING DATES FROM 20160802 TO 20160815;REEL/FRAME:040087/0730 |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1551); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Year of fee payment: 4 |